Q. E. D., or New Light on the Doctrine of Creation eBook

afterwards appointed Abbot of Bruenn, had in the year
1865 published the results of his experiments in breeding,
which had been ignored or forgotten until rediscovered
in 1900 by de Vries and two others simultaneously.
From this point Mendelism, as it is now called, has
steadily gained ground, until at the present time it
can be said to be the dominating conception among
biologists the world over regarding the problems of
heredity.

Mendel worked chiefly with peas, crossing different
varieties. In his methods of investigation he
differed from all previous investigators in concentrating
his attention upon a single pair of alternative or
contrasted characters at a time, and observing how
these alternative characters are transmitted.

Thus when he crossed a tall with a dwarf, giving attention
to this pair of contrasted characters alone, he found
that all the first hybrid generation were talls, with
no dwarfs and no intermediates. Accordingly he
called the tall character dominant, and the
dwarf character recessive, and a pair of contrasted
characters which act in this way are now called factors
or sometimes called unit characters. But
on allowing these hybrids to cross-fertilize one another
in the usual way, Mendel found that in the second
generation of hybrids there were alwaysthree
talls to one dwarf out of every four. Further
experiments proved that these dwarfs of the second
hybrid generation always bred true, that is,
one out of four; and that one out of the remaining
talls always bred true, making another quarter of the
total; while the remaining fifty per cent. proved
to be mixed tails, always acting as did the original
hybrids, splitting up in the next generation in the
same arithmetical proportion as before.

Accordingly, if we confine our study to the two contrasted
characters, tallness and dwarfness, we see that just
three kinds of peas exist, namely, dwarfs which breed
true, talls which breed true, and talls which always
give the same definite proportion of talls and dwarfs
among their descendants. Innumerable experiments
which have since been made with other pairs of characters
have demonstrated that this same mathematical proportion
holds good throughout the whole world of plants and
animals;[25] and hence this astonishing result is now
called Mendel’s Law, and is regarded as the
most important discovery in biology in several generations.

[Footnote 25: When dealing with only a few individual
cases, we do not always find them to come out in such
exact proportion; but when the number of examples
is large, the proportion is so close to these figures
that the exceptions can be entirely neglected as probably
due to error of some kind.]